Cord/adapter needed to connect MacBook Pro (16-inch, 2021) to iMac (21.5-inch, Late 2012)

I’m trying to connect MacBook to Mac monitor. MacBook Pro is 2021, but monitor is from 2011

It will not work because your Macbook Pro is too new. Target Display Mode (TDM) is fully deprecated and no Mac made after 2019 can send a video signal to one of the limited number of iMac sub-models that could act as a monitor for another Mac.

The very restrictive hardware and OS requirements of TDM are laid out in this Apple article:

Use your iMac as a display with target display mode - Apple Support

bfitzsimmons74 wrote:

What cord/adapter is needed to connect MacBook Pro (16-inch, 2021) to iMac (21.5-inch, Late 2012)?

To what end...ie for what purpose...?

If you are trying to move to a new machine, use a backup drive that has USB out if that is your issue

ref: USB-C to USB Adapter

The most trouble free way to move to a new machine, is using the Setup Assistant on the initial boot of a brand new machine— you have one shot here. Set up your MacBook Pro - Apple Support

The second best way is use the Migration Assistant.

How to move your content to a new Mac Transfer to a new Mac with Migration Assistant - Apple Support

Target Disk Mode is no longer support.

ref: https://support.apple.com/en-us/HT204592

You can look at the system requirements for Airplay

Use AirPlay to stream video or mirror the screen of your ...

System requirements for Continuity on Mac, iPhone, iPad, ...

Set up your Mac to be an AirPlay Receiver